Examine source code of Youtube Timer

{
  "manifest_version": 2,
  "name": "youtube-timer",
  "version": "1.0",
  "description": "Adds an annoying timer",
  "browser_action": {
    "default_icon": "icons/YTT2.png",
    "default_title": "Youtube Timer",
    "default_popup": "popup/youtubetimer.html"
  },
  "icons": {
    "196": "icons/YTT2.png"
  },
  "background": {
    "scripts": [
      "background/script.js"
    ]
  },
  "permissions": [
    "*://www.youtube.com/*"
  ]
}